Proficiency test for clearance mixed-nuclide samples.

In 2010, the National Radiation Standard Laboratory held a proficiency test for measurement and analysis of clearance mixed-nuclide samples. Two types of samples, box-shape and drum-shape, containing (60)Co and (137)Cs mixed solutions were measured by the participating laboratories and their results were then compared with the reference values. Seven participants used plastic scintillator counting systems and two participants used HPGe spectrometer systems to join in this study, obtaining 40 measurement results. The evaluation results showed that all the participants passed the requirements of this proficiency test, E(n)≦1, and the discrepancy was between -25% and 50%.